The electronic conductivity of transition metal oxides, is generally lower than the electronic conductivity of transition metal sulphides. It is possible to make battery cathodes containing transition metal sulphide active material and a binder. However, it is necessary to add carbon to the composite cathode when the active material is based on an oxide. The requirement for carbon and the amount thereof depends, to some extent, on the specific oxide. The electronic conductivity of vanadium oxides decreases substantially (2-4 orders of magnitude) during lithium insertion upon discharge of a battery. This increases the need for even greater amounts of added carbon. The amount of carbon added is usually equivalent to about 40-50% by volume of the cathode mixture. This depends on the relative densities of the carbon and the other components in the cathode. Methods which allow reduction of the carbon content are important in order to increase the specific energies of the battery.
Current batteries contain high surface area oxide powders obtained by milling of precursor material. Current methods for the manufacture of powders involve mechanical grinding of precursor material prepared, for example, by rapid quench of molten material or by precipitation from an aqueous solution. As a result, the precursor material is in the form of lumps or large particles. By standard milling techniques it is difficult to reduce the lumps to less than 100 micrometers and very difficult to grind them to less than 10 to 50 micrometers. Smaller particle sizes are desirable because the larger the surface area, the higher is the current drawn from a battery while the current density on the surface of the active material remains low which allows high utilization of the active material.